The present invention is related generally to apparatus for controlling the outflow of flushing water from a toilet flush tank into a toilet bowl, and more particularly, to a ball valve for toilet flush tanks which tends to close before all of the water is drained from the flush tank during a flush.
Most conventional toilets of the type having a flush tank for storing water for use in flushing typically have a flush water volume capacity sufficient to satisfactorily flush solid matter, such as fecal waste, out of the toilet bowl. However, such capacity, while necessary for flushing solid waste, is excessive for normally flushing liquid waste, such as urine. Therefore, since the majority of flushes are used for flushing only liquid waste, an excessive amount of water is wasted during normal use over a period of time. Recent water shortages in several parts of the country, as well as a general increased awareness and concern for conservation has fostered searches for more effecient flushing or control devices for toilets to minimize the waste of water.
Most of the effort in developing more efficient toilet flushing devices has been directed to mechanisms which allow the user to select a flush utilizing the full capacity of the flush tank for flushing solid matter, or, in the alternative, utilizing only a portion of the water stored in the flush tank for flushing liquid waste. One of the more common approaches to solving the problem has been to provide dual drain outlets in the flush tank, with one outlet having a low elevation near the bottom of the flush tank, and the other outlet having a higher elevation in the range of midheight in the flush tank, each outlet having a separate ball valve mounted thereon that can be selectively opened by the operator, depending upon the amount of flush water desired. Typical of these inventions are the U.S. Pat. No. 2,505,091, invented by E. Brebis, U.S. Pat. No. 2,731,647, invented by E. Groth et al, U.S. Pat. No. 3,869,733, invented by C. White, U.S. Pat. No. 3,903,551, invented by A. Johnson, and U.S. Pat. No. 4,011,604, invented by F. Goldsworthy. While most of these inventions provide selective volume flush capabilities, most of them have several drawbacks. For example, flush tanks with conventional single volume flush mechanisms must be disassembled in order to be refitted with the dual capacity flush apparatus of these inventions, and relatively complex dual flush actuator and control mechanisms are required. Consequently, they are more expensive to to manufacture and they are very inconvenient for retrofitting existing single flush toilets with the dual flush mechanisms.